Duterte back peddled in 2017, and said he would only cooperate if a probe was not led by Callamard.

Philippines President Rodrigo Duterte has told police and soldiers not to participate in any probes against his bloody war on drugs, Reuters reported Friday.

In a speech delivered to elite armed police forces in Davao City, Duterte said: "When it comes to human rights, or whoever rapporteur it is, my order to you: Do not answer. Do not bother."

Duterte's comments come amid local and international pressure to investigate the killing of thousands of Filipinos by police units since Duterte took office in 2016, with rights groups claiming the number could be over 12,000.

Duterte defended his order towards security services, saying: "Who are you to interfere in the way I would run my country? You know very well that we are being swallowed by drugs."

In 2016, the Philippines government formally invited Agnes Callamard, the UN rapporteur on extra-judicial executions, to investigate Duterte's controversial killings. However, Duterte back peddled in 2017, and said he would "slap" Callamard if she began her investigation.

On Tuesday, Duterte stated he would accept a UN investigation into his hallmark drug policies, but said he would not cooperate if it was led by Callamard, who he has accused of bias.

Last month, the International Criminal Court (ICC) opened a separate examination into deaths linked to Duterte's "war on drugs." The investigation could lead to charges of crimes against humanity, but the process may take years.

Duterte responded by saying, "If you want to find me guilty, go ahead. So be it. Find a country where they kill people with a firing squad and I'm ready."

Human rights groups have said many of the killings by police have been executions, an allegation which law enforcement deny.

In November, surveillance footage surfaced showing anti-drug officers shooting and killing three men. It took them nearly half an hour before attempting to move the bodies and take them to hospital

The raids occurred the day after Duterte ordered police to leave anti-drug operations to the state-run Drug Enforcement Agency.